1. Field of the Invention
The present invention relates to a cartridge, which houses a recording medium and has a write protect portion for switching between a write-allowed state and a write-inhibited state, and a drive device using the same.
2. Description of the Related Art
Disk-type media, such as an optical disk, a magneto-optical disk, etc. have been used as recording/reproducing media for portable computers, for example. When information is to be recorded into or reproduced from such a disk medium, the disk medium is loaded in a disk drive and a laser beam is irradiated onto a recording face of the disk medium while the disk medium is being rotated. The recording of the information on the disk medium is performed by a formation of pits due to decomposition of a dye layer, phase variation, magnetization or the like, of the recording face. The recorded information is reproduced from the disk medium on the basis of variation in reflectivity or polarization angle of the laser beam.
In order to enhance the storage capacity of this disk media, shortening the wavelength of a laser beam to be irradiated onto the recording face has been proposed. When information recording or reproduction is carried out using a short-wavelength laser beam, for example, a blue-violet laser beam, the laser beam is attenuated by a cover layer for protecting the recording face of the disk medium. In order to suppress the attenuation of the laser beam due to the cover layer, the thickness of the cover layer is required to be small. When the thickness of the cover layer is reduced as described above, the diameter of the spot of the laser beam on the surface of the cover layer (a surface exposed to the outside) is reduced, so that the influence of dust or the like adhering to the surface of the cover layer cannot be ignored.
Therefore, a disk cartridge having a case which houses a disk medium to prevent adhesion of dust or the like to the disk medium has been adopted. This disk cartridge is structured to have an opening through which the center hole portion formed at the center portion of the disk medium and a part of the recording face (cover layer) of the disk medium are exposed to the outside, and a shutter member for opening and closing the opening. With this construction, the opening of the disk cartridge is closed by the shutter member when the disk medium is not being used, thereby preventing an invasion of dust or the like into the disk cartridge, that is, the adhesion of dust or the like to the disk medium. When the disk medium is being used, the closing of the opening by the shutter member is released in connection with the loading of the disk cartridge into the disk drive device, so that the center hole portion of the disk medium can be held by a rotating spindle shaft and a laser head for irradiating a laser beam onto the recording face of the disk medium can approach the disk medium.
The disk cartridge described above comprises a write protection portion for preventing an mis-deletion of data recorded on a disk medium. Further, the write protect portion includes a switching member for switching between a write-allowed state (in which data can be written into the disk medium) and a write-inhibited state (in which data cannot be written into the disk medium).
For example, as shown in FIGS. 24 and 25, a compact tabular mis-deletion preventing plug 862 serving as the switching member is fitted in a recess portion 872 formed in the case 870 of a disk cartridge 860 so as to be slidable along the surface of the case 870. A through-hole 874 is formed in the recess portion 872. When the mis-deletion preventing plug 862 is located at the write-inhibited position (unrecordable position), the through-hole 874 is exposed in the form of a small window to the outside. On the other hand, when the mis-deletion preventing plug 862 is located at the write-allowed position (recordable position), the through-hole 874 is closed and thus it is not exposed to the outside.
When data are to be written into the disk medium, the mis-deletion preventing plug 862 is shifted to the write-allowed position as shown in FIG. 24. Accordingly, when the disk cartridge 860 is loaded into a disk drive device (not shown), an abutting rod 876 disposed in the disk drive device abuts against the mis-deletion preventing plug 862 and the disk drive device recognizes that data are writable (recordable) into the disk medium.
On the other hand, when data writing is inhibited, the mis-deletion preventing plug 862 is shifted to the write-inhibited position as shown in FIG. 25. When the disk cartridge 860 is loaded into the disk drive device, the abutting rod 876 does not abut against the mis-deletion preventing plug 862, and is inserted into the through-hole 874, so that the disk drive device recognizes that data are inhibited from being written into the disk medium (i.e., write-inhibition).
When the disk cartridge is set to the write-allowed state and then loaded into the disk drive device, the abutting rod 876 provided to the disk drive device abuts against the mis-deletion preventing plug 862 at all times. Therefore, there is a problem that dust occurs at the abutting site and the dust control performance is lowered. Further, the surface shape of the mis-deletion preventing plug 862 varies mainly due to roughness caused by damage, wear-out, etc. of the surface of the mis-deletion preventing plug 862, and thus there is also a problem that the disk drive device carries out mis-detection, that is, it makes a mistake between the write-allowed state and the write-inhibited state.
This problem occurs not only in the disk cartridge, but also in general to cartridges in which a recording medium is housed.
Further, when disk media are designed in high density (normally, the track pitch or track width is reduced) and with enhancement of the storage capacity of the disk medium, a lower capacity disk drive device, which can support only disk media having lower storage capacity, can neither record information into higher capacity disk media (having a larger storage capacity) nor reproduce information from the disk media.
It is also preferable that information, such as pre-recorded information, and the like, which is recorded on disk media having lower recording capacities, be recordable and reproducible by a disk drive device, which also supports disk media having higher recording capacities. Namely, it is preferable that downward compatibility be established when there are multiple types of a disk cartridge, which have the same shape but accommodate disk media of different recording capacities. (Hereinafter, a higher storage capacity and a lower storage capacity will be referred to as, “higher capacity” and “lower capacity”, respectively.).
A downward compatible disk drive device can recognize the storage capacity (track pitch or track width) of a loaded disk medium in the process of reading data recorded on the disk medium, and adjust the recording or reproducing state in accordance with the storage capacity of the disk medium. Accordingly, if the storage capacity of the disk medium can be specified before the data are read out from the disk medium, the adjustment corresponding to the storage capacity of the disk medium could be made in advance. Therefore, the idle time could be shortened, that is, the response of the disk drive could be enhanced.
From this viewpoint, a disk cartridge and a disk drive in which an identification hole for identification of storage capacity is provided to a case of the disk cartridge and the storage capacity of the disk medium is identified on the basis of a judgment as to whether a detection member of the disk drive device can be inserted into the identification hole or not are known. According to the disk cartridge and the disk drive device as described above, two different recording capacities can be distinguished from each other with a simple construction.
However, it is difficult in such a conventional storage capacity identifying technique to discriminate many different recording capacities from one another. Further, it is required to prepare for many cases in which identification holes are respectively located at different positions in accordance with the recording capacities of the disk media. This makes the parts management more cumbersome, and increases the number of metal molds used to manufacture cases, and the manufacturing cost of disk cartridges.